No Cabin Heater after EGR Blank

[Ben Griffith]

Hi Gents,

We were having this discussion in another thread of mine about a black smoke issue that was solved after putting in a blanking plate, which successfully diagnosed the EGR valve as faulty. However afterwards myself and at least one other gent had the same issue of heat loss in the cabin after doing this, so I thought it warranted a discussion of its own.

To re-cap, after fitting an egr blanking plate to the intake/drivers side of the engine, my black smoke and power issue resolved, however afterwards there was intermittent heat flowing through the EGR cooler pipes which then feed to the heater core, therefore intermittent and only lukewarm cabin heat even with the dial on max.

I've mucked about with it all weekend thinking it would be air bubbles in the coolant, as I also replace the elbow going into the heater core a few weeks ago after it leaked. I am now confident that it is not an airlock issue.

What I really think is happening is that with the EGR blanked, there is no longer hot exhaust gases being drawn through the pipe, therefore as soon as the main fan kicks in, it is cooling the coolant at the EGR cooler so much without that additional heat that the coolant is actually cold or lukewarm at best by the time it reaches the heater core, hence cool air even on max. My questions to the group are:

1. Has anyone else experienced this - noting that I've only mechanically blanked the EGR pipe, with my 2009 titanium there were no error codes after doing this so therefore did not perform any ecu delete

2. I could bypass the EGR altogether with a piece of heater hose, to at least diagnose this as the issue. Has anyone done this and are there any other knock on effects it could have? Obviously it would immediately raise suspicion from mechanics doing pink slips or RTA vehicle inspectors, but what about mechanically?

3. What is the default temp the main fan kicks in? Can this be adjusted anywhere? Maybe turn it off to test my theory at least? Is there a relay that can be pulled to disable it at least for testing?

Any general thoughts welcome. Many thanks gents.

Cheers

 

[Old.Tony]

The coolant that flows into the heater matrix inside (that provides the cabin with heat) is not heated by the EGR cooler. The EGR cooler is designed to use the coolant to cool down the hot exhaust gas before it hits the intake manifold. If you block the EGR valve, the largest effect you give to the motor is the removal of hot exhaust gas from the intake. There is a very minor change in coolant temp because when the EGR valve is open and hot exhaust is flowing (note that it doesn't flow all the time) there is a small rise in coolant temp - but it's not much, because the cooler is so small it doesn't really get a lot of a chance to heat the coolant up.

You could bypass the EGR cooler (if you're going to replace the EGR valve and unblock the EGR tube, this should be temporary only). You could also undo both of the coolant hoses from the firewall and try pumping water through it to see if there's a blockage, but don't use a lot of pressure in case the blockage decides to vent itself in other ways inside the cabin!